diff --git a/src/xous/definitions.rs b/src/xous/definitions.rs
new file mode 100644
index 0000000..142967f
--- /dev/null
+++ b/src/xous/definitions.rs
@@ -0,0 +1,79 @@
+#[derive(Debug, Copy, Clone)]
+pub enum SyscallResultNumber {
+    Ok = 0,
+    Error = 1,
+    MemoryRange = 3,
+    ConnectionId = 7,
+    Message = 9,
+    ThreadId = 10,
+    Unimplemented = 12,
+    Scalar1 = 14,
+    Scalar2 = 15,
+    MemoryReturned = 18,
+    Scalar5 = 20,
+}
+
+#[derive(Debug)]
+pub enum Syscall {
+    Unknown([i64; 8]),
+    IncreaseHeap(
+        i64, /* number of bytes to add */
+        i64, /* memory flags */
+    ),
+}
+
+#[derive(Debug)]
+pub enum SyscallNumber {
+    MapMemory = 2,
+    Yield = 3,
+    IncreaseHeap = 10,
+    UpdateMemoryFlags = 12,
+    ReceiveMessage = 15,
+    SendMessage = 16,
+    Connect = 17,
+    CreateThread = 18,
+    UnmapMemory = 19,
+    ReturnMemory = 20,
+    TerminateProcess = 22,
+    TrySendMessage = 24,
+    TryConnect = 25,
+    GetThreadId = 32,
+    JoinThread = 36,
+    AdjustProcessLimit = 38,
+    ReturnScalar = 40,
+    Unknown = 0,
+}
+
+impl From<[i64; 8]> for Syscall {
+    fn from(value: [i64; 8]) -> Self {
+        match value[0].into() {
+            SyscallNumber::IncreaseHeap => Syscall::IncreaseHeap(value[1], value[2]),
+            _ => Syscall::Unknown(value),
+        }
+    }
+}
+
+impl From<i64> for SyscallNumber {
+    fn from(value: i64) -> Self {
+        match value {
+            2 => SyscallNumber::MapMemory,
+            3 => SyscallNumber::Yield,
+            10 => SyscallNumber::IncreaseHeap,
+            12 => SyscallNumber::UpdateMemoryFlags,
+            15 => SyscallNumber::ReceiveMessage,
+            16 => SyscallNumber::SendMessage,
+            17 => SyscallNumber::Connect,
+            18 => SyscallNumber::CreateThread,
+            19 => SyscallNumber::UnmapMemory,
+            20 => SyscallNumber::ReturnMemory,
+            22 => SyscallNumber::TerminateProcess,
+            24 => SyscallNumber::TrySendMessage,
+            25 => SyscallNumber::TryConnect,
+            32 => SyscallNumber::GetThreadId,
+            36 => SyscallNumber::JoinThread,
+            38 => SyscallNumber::AdjustProcessLimit,
+            40 => SyscallNumber::ReturnScalar,
+            _ => SyscallNumber::Unknown,
+        }
+    }
+}